1. Field of the Invention
The present invention relates to a method for making a mark on the surface of a semiconductor device. The present invention also relates to a semiconductor device marked by the marking method.
2. Background of the Art
Conventionally, various types of semiconductor devices have been proposed. Such a semiconductor device may be printed, on its upper surface, with some characters or marks representing e.g. the model name of the device.
A conventional method for printing on a semiconductor device is described in Japanese Laid-open Patent Publication No. 2002-134660, for example. By this method, as illustrated in FIGS. 6A and 6B of the accompanying drawings, several marking members are embedded in the surface of a semiconductor device.
Specifically, referring to FIG. 6A, a semiconductor chip 91 is mounted on a substrate 92 supported by a lower molding member 90, and an upper molding member 93 is arranged above, facing the lower molding member 90. A transfer sheet 95 carrying marking members 94 is attached to the lower surface of the upper molding member 93. A sealing resin 97 is loaded into the space between the lower molding member 90 and the upper molding member 93 to seal the semiconductor chip 91 and the substrate 92.
Then, as illustrated in FIG. 6B, the transfer sheet 95 is detached from the hardened sealing resin 97, while the marking members 94 are left in the sealing resin 97. The embedded marking members 94 are arranged to provide information for identifying the semiconductor device, and thus the model name of the device can be recognized.
The conventional printing method, however, may cause inconvenience as follows. As seen from the above explanation with reference to FIG. 6A, the marking members 94 need to be attached to the transfer sheet 95 firmly enough so as not to be carried away by the sealing resin 97 being loaded. On the other hand, the same marking members 94 should be detached from the transfer sheet 95 to remain in the resin 97 (see FIG. 6B) when the sheet 95 is removed from the resin 97. Such an ideal behavior of the marking members 94 may not always be expected, and in some cases, incomplete printing may result due to the missing of one or more marking members 94. Such incomplete printing may occur more often as the semiconductor device (and hence each marking member 94) is smaller in size. Further, according to the conventional printing method, the respective marking members 94 need to be positioned accurately on the transfer sheet 95. Such accurate positioning, however, becomes more difficult as the individual marking member 94 is smaller.